Gavin Mitchell appears during Season 9 in "The One Where Rachel Goes Back to Work" to "The One Where Monica Sings." He is portrayed by Dermot Mulroney.
Summary
Still on maternity leave, Rachel visited work to find Gavin to have rearranged her office and being favored over her by her boss. She decides to go back in worry that she may lose her job by him. At first she found him very rude but after he offered to look after Emma while she had a presentation she found that very kind. In the next episode, despite what she says, she quite likes him. Though she appears cross when Monica accidentally invites him to Rachel's birthday party. she is actually kind of pleased.
He does come once the party finishes, but bought her a present a card that said simply "From Gavin." Rachel gets annoyed with him again but they kiss on the balcony which Ross sees from his apartment.
Their romance is short lived when he notices that Rachel and Ross's relationship is very complicated and Rachel is still unsure of her feelings so they decide not to do anything. He is not seen again during the show.